Frequently Asked Questions - FAQ's
Q. I thought a cobot was safe?
A. Cobot manufacturers have done a fantastic job in creating a safe cobot. However, this is before any tooling or gripper assembly is added or any part is picked and placed. This is where the application and use potentially becomes unsafe. I've seen cobots that have been installed to be collaborative, only for them to end up in a guard solution because somewhere along the way the design concept has been misunderstood.
Q. When should the risk assessment be conducted?
A. As early as possible! Don't leave it until the end (although it is quite a common approach to do this). Being involved from the beginning of the concept, will only aid the design and the safety can be built in as part of this. No matter where you are within a project, get in touch and lets discuss your options.
Q. What if the cobot is planned to have more than one use?
A. No problem. Each application requires assessing to ensure that in all applications, it is safe for all to use.
Cobot Common Mistakes
Assuming that cobots are inherently safe
Yes, cobots are a safe alternative to traditional industrial robots. They are designed to operate or work around humans, however, this doesn't mean that they are safe. You need to assess them on an application basis. It is often assumed that cobots are safe in all situations. As a result, they can end up performing dangerous actions with the cobot.
Not doing a risk assessment
It is critical when implementing cobots to have a detailed risk assessment. You need to properly assess all aspects of the task and judge its overall safety. Unfortunately, some people think that they can bypass the risk assessment when it comes to cobots. This is not a good idea!
The detail within the risk assessment
One of the most common mistakes with cobots is capturing the correct detail in the risk assessment. A rough outline of the task will show a basic operation, but won't go into enough detail to identify the potential safety issues. The flip side to this is over-complicating the risk assessment. Too much detail and things could be easily lost. Keep the functional requirement specification separate from the risk assessment.
The cobot and its installation is defined as a machine and is subject to all the legal requirements of the machinery directive and other applicable directives. This must be fully risk assessed and the technical file built and retained for 10 years. Within the UK, the requirements of PUWER, also need to be met. Currently the guidance for collaborative robot safety can be found in ISO/TS 15066
Failing to account for end tooling
The safety limits of collaborative robots only apply to the robot itself. The end of arm tooling you choose for the application and the part you handle can have a huge impact on the overall safety of the robot and the application. Long parts could extend beyond the work-space. Just because the cobot won't go outside the workspace doesn't mean the part won't. What about weight? If the part is heavy it could fall to the floor, injuring a person. The cobot application could be safe but the risk assessment should capture the end of arm tooling and parts being handled and any hazards that either of these may create
Only considering normal operation
Issues often occur when something unexpected happens. The risk assessment needs to consider both foreseeable and unforeseeable hazards. Consider the 'what ifs'. There's no such thing as a stupid question.
Only considering the risk from one operation
It is easy to consider the risks based on normal operation. Cobot applications have many different steps to create a working process. All of these affect the safety of the overall task. Give consideration to those tasks that are not an operation
Not involving the relevant people
A risk assessment created by a single person may capture certain hazards, but they may not see everything that poses a risk. Having those who will use or maintain the cobot application involved is a key element to the overall safety process.
Using a risk assessment to justify a decision
There are cases where people have used the risk assessment to justify decisions which have already been made.
For instance, a person might decide they don't want to purchase a laser safety scanner, so they use the risk assessment to show that one is not needed. This can be seen as a method to justify what can be seen as an unsafe solution